Beginning with the first election held after the Representation of the People Act 1918, which
allowed all men aged over 21 and some women over 30 to vote, the data allows
users to trace the decline of the Liberals and the rise of Labour, the strength
of the Conservative and Labour Parties in the post-war period, the re-birth of
multiparty politics from the 1970s, and the growing political divergence
between the nations and regions of the UK.

We hope to add further detail to the data, such as the
gender of candidates and maps of results, in the coming months.

To mark its launch, we’ve pulled out some key facts from the data. Want to know which winning candidate had the greatest number of votes? The closest four-way contests? Or the smallest majorities? Then read on…

The largest and smallest electorates

The largest ever electorate since 1918 was recorded in Essex Romford, where 167,939 were registered at the time of the 1935 General Election. The five smallest recorded electorates (excluding those of university seats) were all in London in 1945, presumably being the result of war damage and depopulation, with the City of London having 10,851 voters.

In the 2017 General Election, the largest electorate was the Isle of Wight, with around 110,000 voters, and the smallest was 21,000 in Na h-Eileanan An Iar (Western Isles).

Prior to 1918, one House of Commons constituency with a strong claim to have the fewest number of electors wasOld Sarum in Wiltshire, which had two MPs and three voters in 1728. But due to the lack of electoral registers for the period, we can’t be certain it was the smallest ever.

The highest and lowest turnouts

Since 1918, turnout in UK general elections has averaged 73%. Due to the low turnout amongst the armed forces and the large number of uncontested seats, the lowest turnout since WWI was the election of 1918. In recent years, the lowest turnout was in 2001 (59%).

In terms of constituency-level turnouts, the five highest
turnouts since 1918 have all been in two constituencies: Fermanagh and South
Tyrone, and Lancashire Darwen.

The five lowest constituency turnouts were all seen in the 1918 General Election. The lowest turnout in recent years was Liverpool Riverside in 2001, at 34%.

Highest and lowest shares of the vote for major parties in Great Britain

The top five vote shares were all achieved before 1945,
while the five lowest occurred in 2015 and 2017.

The highest Liberal/Liberal Democrat vote share was recorded in Caernarvon District in 1924, with 82.5% of the vote. The Liberals did not stand candidates in many constituencies during the lowest-point of the party’s fortunes in the 1940s and 1950s. If they had, poorer performances could have been registered than those in 2015 and 2017.

The lowest Conservative vote share recorded in Great
Britain was seen in Glamorganshire Pontypridd in 1918, where the party received
1.1% of the vote. Labour recorded its worst general election vote constituency
vote share in Glasgow Bridgeton in 1935, receiving 2.2% of the vote.

The highest SNP vote share at a general election was
recorded in the Western Isles in the February 1974 General Election, at 67%.

Plaid Cymru received its highest vote share at Caernarfon in 1992 (59%).

Largest and smallest majorities since 1918

The largest
majorities by percentage of votes in the UK have tended to occur in Northern
Ireland. In both 1955 and 1959, the Ulster Unionist candidate George Currie was only opposed
by Sinn Féin in Down North, resulting in his 96% majority in 1959 and one of 94%
in 1955.

Between the traditional three major GB parties, the largest majorities occurred in 1918 and 1945. In the 2017 General Election, Liverpool Walton had a Labour majority of 77% over the Conservatives (86% to 9%), and in Knowsley the Labour majority was 76% (85% to 9% Conservatives).

The largest
majorities by number of votes in Great Britain coincided with the strongest
electoral showings of the Conservative Party under the National Coalition
Government in 1931 and 1935, when the party won more than 50% of the vote in
both elections. The largest Labour majority was recorded in Knowsley in 2017,
gaining more than 47,000 votes and 85% of the vote.

The smallest majorities, in contrast, occurred when the party system was in relative flux, being associated with the stronger performances of parties other than Labour and the Conservatives.

Smallest majorities in UK general elections since 1918

Winner

Second

Vote margin

Election

Derbyshire Ilkeston

National Labour

Labour

2

1931

North East Fife

SNP

Liberal Democrat

2

2017

Winchester*

Liberal Democrat

Conservative

2

1997

Tiverton

Liberal

Conservative

3

1923

Leeds West

Labour

Conservative

3

1924

Peterborough

Conservative

Labour

3

1966

Carmarthen

Labour

Plaid Cymru

3

Feb 1974

*The result was voided in the High court shortly after

Closest three and four-way contests

The closest three-way result was in Caithness and
Sutherland in 1945, where 0.37% of the vote separated the first and
third-placed candidate. The sitting MP and Liberal Leader, Archibald Sinclair, fell
from first to third place, but remained only 61 votes behind the
Unionist/Conservative winner. He stood again in 1950, moving to second place in
another close contest, losing to the Conservative candidate by 1.4% of the
vote.

Recent close three-way contests have not included the ‘traditional’
trio of Conservative, Labour and Liberal Democrat. The close contest in Lanark
and Hamilton East in 2017 was between the SNP, Labour and Conservatives. In
2015 less than 1.25% of the vote separated the Conservatives, Labour and UKIP
in Thurrock.

Recent four-way marginals reflect the growth of the Greens, SNP and Plaid Cymru.